Apparatus for continuously colorimetrically analyzing fluids for chemical components



1951 H. FUHRMANN 2,995,425 APPARATUS FOR cowrxuuousw COLORIMETRICALLY ANALYZING I mums FOR CHEMICAL COMPONENTS Filed Dec. 1a, 1958 INVENTOR'. FUHRMANN HANS ATTYS,

v having-chemical components therein.

The present invention relates broadly to apparatus for determining continuously chemical components or constituents in fluids, and more particularly to apparatus for continuously and automatically determining chemical components in fluids by colorimetric analysis.

Heretofore apparatus has been utilized to determine chemical contents of fluids in a continuous and fully automatic process by introducing reagents, indicators, buffers and the like into, or into contact with, a fluid Such apparatus have-been utilized to test for hardness of water for different applications, silica, phosphate, chlorine content, etc.

Some known apparatus of] this nature based upon a colorimetric principle haveuti'lized reagents inthe nature of solid rods which act as indicators, butters, etc, and which solid rods are openly introduced into a mixing vessel wherein they are contacted by the fluids that are to be tested. Color of the fluid contacted by the solid reagent rods is alfected by the reagent which is washed off or dissolved into the fluid, and this results in a color change depending upon the chemical constituent in the fluid being sought, and which color isflbrought about by a chemical reaction between the chemical content and the reagent. In some intance's the amount of color change is, measured colorimetrically to give a quantitative value of content of the chemical being sought. The composition of the reagent rod used is varied, dependent upon requirements for colorimetrically indicating specified chemicals in the fluid. Additionally, the reagent rods can contain additional substances in the nature ofbuifers etc. Such reactions, and chemical reagents required, to

' the reagent reaction rod is physically separated from a mixing chamber or vessel by means of a fluid pervious I diaphragm in such a manner that reagent from the reagent rod is mixed with the liquid by dilfusion through the diaphragm, thus providing improved results by preventing contamination of the reagent and; or accumulation of crystals or the like on the rod which mightotherwise alter its eflective transmission of the reagent to the fluid. Additionally, the present invention, due to the arrangement ofthe reagent rod out of direct cont-act. or

immersion in the fluid, insures an equal reaetance face "area 01? the: rod wi h respect. t the fluid through h diaphragm.

Additionally, the present invention teaches apparatus 'for colorimetrically testing fluids continuously, and which has outstanding reliability in action due to lack of moving parts and valves or the like, the entire system and apparatus functioning; automatically, continuously and by gravitational flow of the fluid, which flow can be regulated as desired.

Other features and advantages of the present invention will be more readily apparent from the following detailed description of an embodiment thereof when ,U j d States Patent C) Patented Aug. 8, 1961 taken together with the accompanying drawing in which the single figure of the drawing schematically depicts an embodiment of the invention.

Referring now in detail to the drawings, the apparatus includes a housing generally designated '10, and which can consist of a block of desired material in which various chambers and passages are provided. An inlet 7 fitting 12 for fluid to be tested is connected into housing 10 and opens into an inlet'fluid channel 14, which charges the sample fluid into an overflow chamber 16 adapted for maintaining a constant volume or head of fluid. Excess fluid flows over a weir lip 18 or the like.

as indicated by. arrow 20. The overflow passes into a fluid discharge channel 22 and drains out of outlet opening 24. vA mixing chamber 26 is provided in housing -10 and is interconnected with the overflow chamber 16 by channel 28. As shown in the drawing, the overflow chamber 16 is situated in a plenum chamber 30 in open communication with the atmosphere by means of vent pipe 32. 1 .v

The mixing chamber 26 extends upwardly through the top wall of housing 10, terminating in an opening 34.

A tubular casing or the like 36, preferably open at both ends, extends downwardly into the upper portion of mixing chamber 26, through opening 34, and is positioned therein by means of flange 38 coating with the topof housing 10 around opening 34. The lower end of tubular casing 36 has a liquid pervious diaphragm 40 secured in the open end thereof. A stick or rod of solid reagent 42 is slidably confined within tubular housing 36, with its lower endresting on and supported by the diaphragm 40. A weight 44 rests on the upper end of reagent rod 42 and maintains the lower end thereof in contact with the diaphragm 40 at all times. In operation, as'liquid passes into and through mixing chamber 26, the lower end'of reagent rod 42, being in contact with the liquid pervious diaphragm 40, will mix the reagent into the liquid by diffusion through the diaphragm.

In order to insure a proper and thorough mixing of the sample-fluid with the reagent in the rod, agitation means are provided including a permanent magnet reagent mixing bar or rod 46, enclosed in glass or plastic, and which is freely movable in all directions in mixing chamber 26. An air gap, transformer 48 or the like is disposed externally of mixing chamber 26 and has a big leakage field. When the transformer is actuated by means of AC. current of for example 50 to cycles, the transformer will cause movement and rotation of the mixing bar 46, which therefore constitutes means for mixing the liquid and reagent which has difi'used through the diaphragm 40.

The so mixed fluid and reagent upon reaction with the chemical provides a color change in the sample fluid dependent upon the chemical constituent being sought, and the nature of the reagent inthe reagent rod, in a known manner to provide a colorimetrically suitable test sample. The so mixed fluid passes from the mixing chamber 26 through channel 50 into an optical measuring chamber 52 through inlet conduit 54 which. is open at its upper end 56 to the atmosphere. The fluid then passes from the measuring chamber 52 through a dis charge conduit 58 which acts as an overflow pipe in overflow chamber 60. Fluid flowing out of conduit 58 into chamber 60 passes into discharge channel 62 flowing to outlet opening 24. Measuring chamber 52 is connected to the atmosphere by means of the open upper end 56 of conduit 54.

The liquid levels in overflow chamber 16 and overflow chamber 36 are fixed by the respective positions of weir 18 and the outlet of conduit 58. This provides a constant water level or fluid level in mixing chamber 26. If desired, the various overflows can be made adjustable and 70 respectively. These plastic so as to permit use of the appliance for ditierent types of analysis. The speed of flow of the sample fluid also depends upon the level dilierence of the two overflows at 20 and 58. Flow of sample fluid is constant and it will be seen that the dissolved reagent from the reagent rod 42 is constantly and substantially instantly mixed and dispersed in the mixing chamber 26 by agitator bar 46.

The measuring chamber 52 has plastic windows 64 and 66 connecting opposed sides thereof with chambers 68 windows 64 and 66 are removable and interchangeable. A light source 72 is housed in chamber 68. A suitable filter 74 is mounted in chamber 70 which can for example permittransmittanoe of between 675 and 725 millimicrons. A photoelectric cell 76 is mounted in chamber 70 behind filter 74. The light source and photoelectric call are connected in operative circuits for their energization. As the sample fluid flows through the apparatus in the manner indicated by arrows, the speed of flow being adjusted as hereinbefore set forth, reagent in substantially equal amounts will be introduced into the fluid and mixed therein to provide a substantially homogeneous mixture. The reagent will cause a color change in the fluid dependent upon the chemical constituent and/ or amounts therein. When measuring contents for hardness such as in boiler feed water, the mixture will take a color tint between red and blue in the mixing chamber 26, and flow'into the'measuring chamber 52 through the various channels shown. It will be noted that a closure plug 78 is provided for overflow chamber 60.

The rod of reagent in the tube 36, and presses with its free end against the wet diaphragm 40 thereby mixing the chemical reagent with the fluid by diffusion. The quantity of dissolved reagent may possibly fluctuate within small limits, however this does not affect the measuring procedure which is adapted to work on a yes-no method of indication in the apparatus, with blue or red colors or others dependent upon the chemical constituent being sought and the constituents in the reagent rod. By altering the contents of the reagent rod, the instrument can be used for testing various fluids. 1

In use, after the reagent rod has been substantially reduced in size by constantly feeding reagent into the sample fluid as explained above, the reagent rod can be easily replaced by a new one so that the appliance is able to continue to act continuously.

It will be noted that the present apparatus permits testing of fluids continuously for chemical constituents therein without the necessity of any moving parts or valves. Of the essence of the invention, the reagent rod does not dip directly into the sample fluid but only touches the surface through the pervious diaphragm. Therefore, in very hard water, for example, an accumulation of calcium and magnesium crystals or the like which would tend to alter dissemination of the reagent in the sample fluid is positively avoided. Additionally, compared to apparatus having a reagent rod dipping into the fluid and which tends to decrease the area of the rod in contact with the sample fluid due to wear, the present apparatus insures an equal dissolving of the face area through the diaphragm for substantially constant results.

The light transmission qualities of fluids being tested for chemical constituents by a colorimetric analysis meth- 0d are well-known, and the use of the photocell for this being loaded is guided verticallypurpose likewise being well-known, a detailed description thereof is not considered necessary.

The apparatus of the present invention has been only schematically shown in the drawings for sake of simplicity and clarity. It is felt that the basic concepts and structure, however, are clearly understandable therefrom. Manifestly many minor, changes in details of construction and arrangement can be elfected within the scope and spirit of the invention without departing therefrom,

as limited solely by the appended claims.

I claim:

1. Apparatus for continuous colorimetric analysis of fluids for chemical constituents comprising a housing, a mixing chamber in said housing, an optical measuring chamber in said housing in communication with said mixing chamber, means for introducing a sample fluid into said mixing chamber, a chemical reagent chamber opening into said mixing chamber, fluid pervious means mounted at the reagent chamber opening adjacent the mixing chamber and incontact with fluid in said mixing chamber, and a fluid soluble solid reagent rod in contact with and supported by said fluid pervious means, reagent being introduced into said sample fluid in said mixing chamber by diffusion through said fluid pervious means.

2. In apparatus for continuous colorimetric analysis of fluids for chemical contents thereof, "a sample fluid and chemical reagent mixing chamber, means for continuously passing sample fluid through said chamber, said chamber having an opening therein, an open end reagent container inserted in said opening and extending into fluid contact in said chamber, a fluid pervious diaphragm closing the fluid contacted end of said container and afluid soluble solid stick of chemical reagent slidably retained in said container and supported to said diaphragm out of direct contact with fluid in said chamber.

3. An apparatus for automatically analyzing chemical components in fluids comprising a circuit for continuously circulating sample fluid to be analyzed, said circuit comprising in the direction of flow a first overflow chamber, a mixing chamber, an optical measuring chamher, and a second overflow chamber, fluid levels in said overflow chambers controlling rate of flow through said circuit and fluid level in said mixing chamber, a reagent container having a lower open end extending in fluid contacting relation into said mixing chamber, fluid pervious means closing said open end withthe lower end thereof in fluid contact, a stick of fluid soluble solid reagent in said container resting on the end of said fluid pervious means remote from said fluid, and indicating means for indicating color change in fluid in said measuring chamber resulting from reaction between the reagent and chemical components in the fluid.

4. Apparatus as claimed in claim 1, and a weight on the upper end of said reagent rod for maintaining diffusing contact thereof with said fluid pervious means.

References Cited in the file of this patent UNITED STATES PATENTS 

1. APPARATUS FOR CONTINUOUS COLORIMETRIC ANALYSIS OF FLUIDS FOR CHEMICAL CONSTITUENTS COMPRISING A HOUSING, A MIXING CHAMBER IN SAID HOUSING, AN OPTICAL MEASURING CHAMBER IN SAID HOUSING IN COMMUNICATION WITH SAID MIXING CHAMBER, MEANS FOR INTRODUCING A SAMPLE FLUID INTO SAID MIXING CHAMBER, A CHEMICAL REAGENT CHAMBER OPENING INTO SAID MIXING CHAMBER, FLUID PERVIOUS MEANS MOUNTED AT THE REAGENT CHAMBER OPENING ADJACENT THE MIXING CHAMBER AND IN CONTACT WITH FLUID IN SAID MIXING CHAMBER, AND A FLUID SOLUBLE SOLID REAGENT ROD IN CONTACT WITH AND SUPPORTED BY SAID FLUID PERVIOUS MEANS, REAGENT BEING INTRODUCED INTO SAID SAMPLE FLUID IN SAID MIXING CHAMBER BY DIFFUSION THROUGH SAID FLUID PERVIOUS MEANS. 